First build, new member = questions

[pliddell]

About a month ago i started working on my first boat, a 12', plywood, 3 chine sailing dingy that i designed using a free CAD program i found online. Maybe a foolish choice for a first time builder, but designing makes it twice as fun for me and i cant stand the look of really hard chines. So far i have built and positioned the frames and stem and laid in the keel. I am just started on laying in chine logs, but as you will see in the photos below (if they work :)) there is one chine were part of it has a reverse angle due to the wineglass transom. How should i best lay in this chine log?
My two ideas (expressed in pictures hopefully):
1. lay chine log (2" by 1")in and cut in a concave V-angle
2. Lay in two 2 by 1's for each surface and then splice them together once the angle becomes flat

design on comp
<img src="http://i270.photobucket.com/albums/jj92/pliddellphotes/design.jpg">

progress so far
<img src="http://i270.photobucket.com/albums/jj92/pliddellphotes/small.jpg">

plan 1
<img src="http://i270.photobucket.com/albums/jj92/pliddellphotes/1.jpg">

plan 2
<img src="http://i270.photobucket.com/albums/jj92/pliddellphotes/2.jpg">

Sorry for any misnamed parts- im new at this
Thanks in advance for any responses.

[Paul Pless]

Welcome to the forum. Your pics weren't showing for me so I edited your urls so they'd show up here. When using photobucket you want to you the 'direct link' address when posting photos to this forum. Goodluck.

[Paul Pless]

Ahhh, I see you got it working now.:)

[Woxbox]

Well, you didn't ask about the design, but I suspect that you suspect that you've run into an unusual construction issue on account of a design that's not common. As I'm sure you know, skegs are usually added to the hull after the hull -- without any reverse angles, is put together. That wide hollow skeg you're building is leaving a wide flat area under the transom, and it's going to drag water and slow you down, probably more than you'd guess. At the very least, if it's not too late, you want to taper that skeg to as narrow an exit as you can get it.

So now that I've got that off my chest...

I'd handle that reverse angle with glass tape and an epoxy fillet. Copper wire or plastic ties will hold the panels in place initially. This will also give you better access to the inside of that skeg when she's all finished. You'll be cleaning a lot of gunk out of that slot!

[pliddell]

sounds good for the reverse chine

with the drag created by the flat back part: my initial plan was to put the rudder right behind that flat spot in the back (and also extend below the hull). If the back of the rudder tapers graudally and the front is even with the back of the hull, then would this still be an issue? there would still be a laminar flow of water after the hull and it would rejoin smoothly after the rudder, right? Just my crazy assumptions- as stated before i have no experience with this :).

[Larks]

Mate, it would seem to me that if there weren't blokes like you giving it a go the way you are we would still be in the stone age. Good on you, it looks great and I'm looking forward to seeing the progress. Can you post a pic of the complete design? Does it have a centreboard and do you know what sort of rig/sail you'll go with?

Also I agree re the reverse chine, stitch and glue - and if you're worried about the skeg becoming a void that fills with all sorts of debris maybe see if you can turn it into a flotation compartment or water tank and glass in a floor over it?

cheers
Greg

[Cuyahoga Chuck]

Planked skegs are not common in hulls that small. The only one I've ever seen was on a old salmon wherry in an John Gardner book.
Current practice is to create an easy to plank bottom with a skeg made from 3/4" plywood glued on. A plywood skeg has one great advantage. It's sacrificial. If it gets chopped up or worn down it's easy to plane off the bad part and glue a repair piece on.

[pliddell]

I should have asked that question a while ago- probably too late to change the shape of the hull now :).

As for the sail plan, I don't have it designed on the computer only on paper, but here's the general idea:
Use the same sail rig that I have on a Laser to save a lot of $. I'll put the mast on the front side of bulkhead 2 and then have my centerboard between B3 and B4. That should give me a lead of about a foot for a slight weather-helm. Does this sound about right? Maybe I'll be able to correct my mistakes before its too late this time.

[Woxbox]

I don't mean to discourage you at all -- there's no better way to learn this stuff than being willing to experiment with a boat. As far as the centerboard, it depends a lot on whether it will drop straight down or angle aft. If you can come up with a way to solidly clamp the mast partner and step in place during initial sea trials to find the best location, you'll be a lot happier with it in the long run by getting it right rather than close.
I'm just eyeballing the photos, but even with a rudder behind that skeg, I think you'll be stirring up a lot of water and generally slowing down the boat, and probably having a less effective rudder. The closer you can pull those garboards in at the sternpost, the better.
Good luck with it. The overall shape looks quite nice.

[Cuyahoga Chuck]

I should have asked that question a while ago- probably too late to change the shape of the hull now :).

As for the sail plan, I don't have it designed on the computer only on paper, but here's the general idea:
Use the same sail rig that I have on a Laser to save a lot of $. I'll put the mast on the front side of bulkhead 2 and then have my centerboard between B3 and B4. That should give me a lead of about a foot for a slight weather-helm. Does this sound about right? Maybe I'll be able to correct my mistakes before its too late this time.

Lasers have three different sails. Like about 5,6 and 7 sq. meters as I recall. The smaller one should be big enough. If you are a Laser sailor you can probably handle whatever you care to hang out. The 5 meter sail is going to urge that thing to the limit if the wind is available. And a centerboard case in hull that short is going to use up a lot of room. A daggerboard is much more tidy but it's your choice.

[DGentry]

You could probably use your Laser foils, as well . . . .

Another thing about the Laser rig: You might note that the mast step on a Laser is actually an oval, rather than round (like the mast). It is oval fore and aft - which allows the rig to rake back a bit when going upwind, and then cant forward when going downwind. That Bruce Kirby is pretty smart.
In a low performance dinghy, it probably won't make much of a difference, but you might consider constructing your mast step in a similar fashion.

I'm no NA, but I agree that the width of your skeg, as shown, is going to create a vast amount of drag.
I'd also stitch and tape those chines, rather than use chine logs - but that's just my personal preference.

Looks good, though! Good luck!
Dave

[pliddell]

When I can't be actually working on my little project posting progress is the next best thing:

all but one chine logs in and getting ready for a trip to Home Depot for some cheap 1/4" ply for planking.
http://i270.photobucket.com/albums/jj92/pliddellphotes/smallstep.jpg

[pliddell]

After much longer than it should have taken, i have finally got all the plywood planks on the side.

Next I plan to fair the hull and then fiberglass, but as a first-timer i have questions.
- What weight of fiberglass? Mainly its for abrassion ressistance, not structural
- How much epoxy resin will I need? I do not plan to coat the inside, just for fiberglassing
- What brand epoxy? I was looking here http://www.uscomposites.com/epoxy.html and they seemed to have good prices but I don't know about quality
- For fairing- I was planning on just mixing in wood flour with the epoxy to make a paste. Acceptable?

Thanks in advance

[L.W. Baxter]

Why glass? You say you used cheap plywood, why not keep it cheap? Plywood planks well glued together will keep the water out.

Save the glass for hull number two, built with marine plywood. In my humble opinion.

[GoldDogs]

glass tape the seams, coat the bare wood with strait epoxy, then fair. Like the guy said, don't put too much into it if its not marine ply.

good epoxys..

System Three

MAS

West- not flexible, amine blush needs to be scrubbed with scotchbrite pad and water between coats(if recoated while epoxy is still wet or dentable you can wait till the last coat to scrub off the blush before fairing)

best go with Slow cure hardner if not too cold there. You want long working times, can always turn up the heat when your done. Keep batches small as mass will accelerate cure times. Fillers will insulate and build up heat, keep the mix small and on a flat surface like a roller tray. Start small till you get used to epoxy and fairing mix. 1/2 or 1 cup at the most to start. mix accurately as per instructions or there could be cure problems. Its not like polyester resin, you can't mix "hot" or cool.

wood flour will be rock hard and very hard to sand. Use Phenolic microballons or some other easy to sand additive. Get a free West users guide for info on fillers/additives and their properties.

http://www.jamestowndistributors.com/userportal/search.do?refineType=1&refineName=Material&refineValue=Epoxy&refine=1&page=GRID&history=o3bnwm7t%7Ctop_category%7Cpage%7EGRID%5Eca tegoryName%7EEpoxy%2Band%2BAdhesives%5EcategoryId% 7E203%5Euser_att_name0%7EUserType%5Euser_att_value 0%7ENewUser

[Woxbox]

On the other hand, if you use that boat on the occasional weekend, and keep it in that garage the rest of the time, you'll still be using it 50 years from now -- whether you cover it with glass or not. It's the boats that live outside that have limited lives.

[Lew Barrett]

I have an OT question. Is there anyone who doesn't have one of those Ridgid shop vacuums as seen poking out of the corner of the first image?:D